This sounds as if your xdebug settings are not correct, the xdebug running in your webserver-instance calls back the ide when a breakpoint is reached. For this to work correctly xdebug must know on which ip address it can find the ide.

Please Check the following entries in your xdebug.ini or xdebug section of php.ini:

When ide and your web server are running on the same machine then xdebug.remote_host = localhost is correct. If your webserver runs on another machine the you need to replace 'localhost' with the ip or the dns-resolvable name of your machine. You also need to make sure that port 9000 is opend for incoming tcp connections on your machine that hosts the IDE.

@kk
It should work
1. If you receive an error message saying something like the port 9000 is occupied (or so ...) then Follow what MiR suggested. This is surely due to a misconfiguration
1. if not go to Tools/options/php and activate Stop at First Line if it is not already activated. Or just make a breakpoint in index.php and see what happens.